Multi-antenna transceivers with beam-forming are recently gaining interest for low GHz frequencies (<6GHz) [1-4]. In the antenna beam, (phase-shifted) signals from multiple antennas add constructively, improving SNR, while out-ofbeam signals add destructively (i.e. spatial filtering). Usually the summation point is behind some gain blocks, which then need to be capable of handling strong signals. To improve the input-referred compression point P1dB, a fully passive switched-capacitor approach was presented in , providing P1dB=+2dBm, but at a high noise penalty: NF=18dB. Here we propose to sum immediately at the baseband capacitors of passive mixer-first switched-RC downconverters. We show that this can render a direction-dependent RF impedance (spatial filtering) together with RF bandpass frequency filtering at lower noise and higher P1dB.
|Conference||IEEE International Solid-State Circuits Conference, ISSCC 2013|
|Period||17/02/13 → 21/02/13|